Radial flow turbine



oct. 21, 1947.

R. O. J. MLL ER RADIAL FLOW TURBINE Filed Dec. 1o,v 1943 2 sheets-shew 12 6 4 I@ 1,7 1,5 r/ VV A@ 7 \\1/ ill \\5 wmf W Mw Y x\.. @W31 1, 1 W

w fi-f" 0d 21, 1947. R. o. J. MLLl-:R

RADIAL FLQW TURBINE Filed Dec. 10, 1945 2 Sheets-Sheet 2 Patente-d Oct.21 1947 RADIAL FLOW TURBINE Ragnar Olov Jacob Mller, Finspong, SwedenApplication December 10, 1943, Serial No. 513,744 In Sweden December 19,1942 (Cl. 25E-16.5)

4 Claims.

Steam or gas turbines of the radial flow type are already known in whichthere are two or more axially spaced blade groups so arranged withrelation to each other as to be passed by the driving fluid insuccession. The object of this well-known construction is to reduce theradial length of the blading and improve the efficiency of the turbineat the same time.

The present invention has for its object to provide an elastic fluidturbine having two or more axially spaced blade groups which whilepreserving the advantages above referred to affords an improved drivingfluid consumption and, in case of bleeding turbines, an improved turbineregulation too.

The invention is characterized, chieiiy, by the fact that the axiallyspaced blade groups are separated from each other by a labyrinth packingor packings so as to represent two individual bladings each adapted tobe operated by an individual one of two separately admitted, parallelstreams of the elastic driving fluid.

Another feature of the invention involves that the division of the bladegroups intotwo separate bladings by means of the labyrinth packing orpackings has reference only to the high pressure section of the turbine,inasmuch as a single low pressure section common to all of the highpressure blade groups is provided, which receives the driving fluid asdischarged from one or more such groups.

In the accompanying drawing three embodiments of the invention areillustrated.

Fig. l is an axial section of part of a turbineV according to the firstembodiment.

Fig. 2 is an axial section of a corresponding part of a turbineaccording to the second embodiment.

Figs. 3 and 4 show effect curves of the turbine shown in Fig. l and Fig.2, respectively.

Fig. 5 is an axial section of part of a turbine according to the thirdembodiment.

With reference to Fig. l, the reference numerals I and 2 designate theend portions or journals of the oppositely rotating turbine shafts. Thejournal I carries two turbine discs 3 and 4,. the former being keyed tothe conical end of the journal and the latter being secured to thejournal by the engagement of its extended hub 5 in the boring of thehollow journal. The journal 2 likewise carries two turbine discs 6 and1:.in this case, however, the former only is directly attached to thejournal, whereas the other disc is carried by the turbine disc 6 throughthe intermedium of a drum-like or cylindrical wall 8 formed integrallywith the periphery of the turbine disc v6 and bolted at its opposite endto the turbine disc 1.

The radially extending passage formed by the space between the turbinediscs 3 and 'I contains a blade'group 9 and the radial passage betweenthe turbine discs 4 and 6 contains av Provided in the radial passageVblade groupr I0. between the turbine discs 'I and 4 which normallyrepresents a connection between the blade groups 9 and IG, and maysometimes contain a blade group, is a labyrinth packing Il thesupporting discs I2, I3 of which are fastened to the turbine discs 'Iand 4, respectively. By this means the two blade groups i9 and IIJ areseparated from each other, so that they are not contained in acontinuous tortuous passage in which they are passed by the drivingiiuid in succession. Instead thereof, each blade group has itsindividual inlet and its'individual outlet. Leading to the blade group 9from an annular passage I5 formed in the turbine casing is a set ofinlet ports I4 extending through the turbine disc `3. To said annularpassage the driving uid, which may be termed steam hereinafter, isadmitted through the pipe I6. The blade group lEl communicates at itsouter` periphery with an exhaust chamber I'I. Leading to the innerperiphery of blade group Ill from an annular passage I9 formed in theturbine disc E is a set of inlet ports I8. The passage I9 receives steamthrough a pipe 2l). A set of outlet ports 2l formed in the cylindricalwall 8 connect the outer periphery of blade group I0 with a separateexhaust chamber 22. Surrounding the annular passages I5 and i9 areoverload or discharge chambers 23, 24.

The exhaust chambers II and 22 are separated from each other .by meansof labyrinth packings 25, 26, the axial thrusts of which balance eachother substantially. In addition to the labyrinth packing I I alreadyreferred to as situated between the two blade groups, a labyrinthpacking 21 is inserted between the stationary turbine casing and theturbine disc 3, another labyrinth packing 28 being provided between thestationary turbine casing and the turbine disc 6. The labyrinth packingII acts not only to separate the blade groups 9 and Ill from each otherbut also to balance the axial thrusts as acting in both directions onthe blade group iI. Leading through the turbine disc 4 and the labyrinthdisc I3 to inner points of the labyrinth packing II are equalizationports 29 in such a way that the outer and inner diameters of theportions of the labyrinth discs I2, I3 situated radially outside saidports are substantially equal to those of the blade group II), the axialthrusts of which will thus be balanced substantially. An equalizationpassage, indicated by the dotted line 3D in the drawing, forms acommunication between the chambers 23 and 24 so that nearly the samepressure will exist on both sides with the exception of the innerportions of the labyrinth discs. Inevitable variations of the axialthrust may be compensated by thrust bearings.

In operation, a flow of steam is admitted through pipe IB to the annularpassage I5 and thence through the ports I4 to the centre of the bladegroup 9 to which the steam imparts its energy while passing outwardlytherethrough and from which the steam is discharged into the exhaustchamber II. Another llow of steam is ad mitted through pipe 20 to theannular passage I 9 and thence through the ports I8 to the centre of theblade group I 0. After imparting its energy to the blade group, thissteam is discharged to the separate exhaust chamber 22. The two iiows ofsteam which may be of the same initial pressure or of different initialpressures are controlled independently. Preferably, the steam pressuresare chosen with a View to producing a lower back pressure in the outletI1 than in the outlet 22. Through pipes 3| steam that has passed through`the labyrinth packings 26 and 28 is allowed to escape to the outlethaving the lowest back pressure.

The turbine above described presents better regulating conditions thanthe hitherto known turbines having two back pressures, that is .to say,turbines of the bleeding type.

In hitherto known turbines of this type governed by throttling, the flowof steam has undergone a throttling operation two times, rstly, at itsentrance into the high pressure section of the turbine and, secondly, atits entrance into the low pressure section thereof, after part of thesteam has been discharged. This operation has caused losses, in part dueto the throttlings themselves, since owing to the governing speed thethrottlings cannot be made arbitrarily small, and in part, and aboveall, at partial loads, as the subdivision of the expansion into twostages impairs the eiiiciency of the partial loads.

The improvement resulting from the invention is diagrammaticallyillustrated in Fig. 3, which shows a curve representing the steamconsumption at throttling. In turbines having blade groups coupled inseries with respect to the flow of the driving iluid the whole turbineoutput iollows curve a. In a turbine according to the invention, onlythe smaller blading I operating at the higher pressure follows curve a.The larger blading 9, on the contrary, which yields the main part of theoutput, follows the lmore Vfavourable curve b.

In Fig. 2 the invention is shown as applied to a back pressure turbineproper. In this case the two blade groups are provided with a commonexhaust chamber I'I. By the removal of the separate exhaust chamber 22of the blade group I0 also the labyrinth packings 25 and 26 may bedispensed with. The remaining elements are designated by the samereference numeral as the corresponding elements of Fig, 1.

Also in this case the admission pressures of the steam may be different,so that the turbine becomes a two-pressure turbine. In case of a mereback pressure turbine the two pressures, however, should be equal atfull load. In such case the length of the blades should be soproportional 4 that the small blading I0 may yield up to 50% of thetotal output and the blading 9 the remainder.

The steam consumption of this turbine is diagrammatically indicated inFig. 4. The curve d has reference to the blading 9 after deducting thelosses appearing in blading I Il, the curve e has reference to theblading I Il after deducting the losses appearing in blading 9, and thecurve c has reference to an undivided turbine governed by usualthrottling. By means of a suitable division of the steam between the twoblade systems 9 and I0 it is possible to obtain a steam consumptioncorresponding to the dotted line (which in part coincides with d and e)when the two blade systems are arranged in parallel according to theinvention.

In the embodiment shown in Fig. 5 the division ofthe blades so as torepresent two or more axially spaced bladings adapted to be passed bytwo or more separate flows of driving uid has reference only to the highpressure part of the turbine. In the low pressure part, on the contrary,there is but a single blade group that is common to all 'blade groups ofthe high pressure part and re ceives driving fluid as exhausted from oneor more of these high pressure groups.

The shafts and the turbine discs are similar to those of the embodimentsalready described and designated by like reference numerals.

The blade group provided between the turbine discs 3 and 1 is subdividedin two sections, namely an inner or high pressure section 91 and anouter or -low pressure section 92. The high pressure section 91 issubstantially of the same radial extension as the blade group IU. Thesection 91 and the blade group I0 are each provided with an individualset of inlet ports I4 and I8, respectively. The blade group I0, however,has no separate outlet nor any exhaust chamber, in as much as thecylindrical connecting wall 8 between the turbine discs 6 and 'I has nooutlet ports (as 2I). Instead thereof the turbine disc I is formed witha set of ports 32 forming a communication between the axially extendingangular passage 33 inside the cylindrical wall 8 and the space 34between the blade group sections 91 and 92.

The exhaust steam from the blading I0 will thus mix in space 34 with thesteam exhausted from the inner blade group section 91 and thenflowtogether with the same through the common low pressure blades 92, thearrangement being such as to allow the discharge of steam from space 34for consumption purposes or the admission of overload steam to the saidspace.

Due to the fact that the high pressure part of the turbine comprisesparallel bladings, the turbine resulting will permit partial governingof the high pressure part which in case of partial loads means animprovement of the efliciency. In case of small loads steam is admittedthrough the ports I 8, while at the same time the admission of steamthrough the ports I 4 is interrupted. The steam ow as supplied throughports I8 passes through the blade groups I0 and 92 in succession whileimparting its energy to the blades of these groups. In case of largerloads steam may be admitted through ports I4, the admission of steamthrough ports I8 being interrupted. In this case the steam expands inthe blade group sections 91 and 92. In case of still larger loads steammay be admitted from both sides, that is to say both through ports I4and through ports I8 so that parallel ows of steam are supplied to thetwo high pressure bladings 91 and I0, while the flows -discharged fromsaid bladings will combine before entering the common low pressureblading 92,

It is to be noted that the number of blade groups and the distributionthereof to separate bladings may be varied arbitrarily without departingfrom the principle of the invention.

What I claim is:

1. In a turbine of the class described, the combination of a stationarycasing having two separate inlets for the driving fluid and at least oneoutlet for exhaust fluid, two oppositely rotatable shafts centrallymounted in said casing so as to extend in axial alinement with eachother, at least four axially spaced turbine discs, two alternate ones ofsaid discs being carried by one of said shafts, one of said other discsbeing carried on the other shaft, a wall secured on said one other discand extending axially outwardly of one of the first two discs, thefourth disc being secured to the said wall and being located between thefirst two discs, a labyrinth packing provided between the inner twodiscs and serving with said discs and said wall as a partition to divideoff in the casing two spaces, turbine blades carried by the respectiveturbine discs in said spaces, passage means to allow separate admittanceof driving fluid to each space from a corresponding one of said inlets,the fluid from one of said spaces exhausting directly to a casingoutlet, an opening in said partition for exhaust of fluid from the otherspace to a casing outlet, so located that the exhausting fluid does notpass through the packing, and labyrinth packings provided between theextreme turbine discs of both spaces and the respective inlets andoutlet of the casing.

2. In a turbine of the class described, the combination of a stationarycasing having two separate inlets and two separate outlets for thedriving fluid and the exhaust fluid, respectively, two oppositelyrotatable shafts centrally mounted in said casing so as to extend inaxial alinement of each other, at least four axially spaced turbinediscs, two alternate ones of said discs being carried by one of saidshafts, the outer one of the other two discs being carried by the othershaft, a support extending axially from said outer disc and passing theinner disc of said one shaft radially outwardly thereof, and supportingthe fourth disc between the first two discs, a labyrinth packingprovided between the inner discs for dividing the space in which thediscs are located into two parts, turbine blades located in said partsof the space and carried by the respective turbine discs, passage meansbeing provided to allow separate admittance of driving fluid to eachpart of the space from a corresponding one of said inlets and separatedischarge of exhaust fluid from each part to a corresponding one of saidoutlets, and labyrinth packings provided between the extreme turbinediscs of both parts and the respective inlets and outlets of the casing,a communication being provided for passing balancing fluid to an innerpoint of said first-mentioned labyrinth packing from the inner end ofthe adjacent blade containing space part, the outer end of whichcommunicates with the outer end of said packing, said communicationcomprising passages extending through the respective turbine disc.

3. In a turbine of the class described, the rotary system of whichincludes two oppositely rotatable shafts extending in alinement of eachother, at least four axially spaced turbine discs, two alternate ones ofsaid discs including an inner disc being carried by one of said shafts,the end one of the other discs being carried by the other shaft, asupporting Wall extending from said end ldisc axially to the other innerdisc, a labyrinth packing provided in the space between the two innerones of said turbine discs for dividing the space in which the discs arelocated into two parts, high pressure blades provided in one of saidparts, other high pressure blades provided in the inner portion of theother part, low pressure bla-des provided in said last-mentioned partoutside the high pressure blades thereof, a stationary casing in whichsaid shafts are centrally mounted and which encloses the rotary elementsof the turbine, said casing having a separate driving fluid inlet foreach groups of high pressure blades and a common outlet for exhaustfluid from all blade groups of the turbine, and said supporting wallbeing located at a greater diameter than the periphery of the adjacentinner disc, an opening through said other inner disc within said wall,said wall and opening constituting fluid conduction means between theinner end of the low pressure blade system and the outer end of the highpressure blade system of said first-mentioned group so that said lowpressure system is fed with fluid discharged from the high pressureblades of both parts.

4. A turbine of the class described, the rotary system of which includestwo shafts for opposite rotation, at least four discs, two alternateones of said discs including an end disc and an inner disc being carried-by one of said shafts, the other end disc being carried by the othershaft, an axially extending supporting wall extending from said otherend disc radially outwardly of and axially -beyond the adjacent innerdisc, the other inner disc being carried by said wall, a labyrinthpacking between the two inner ones of said oppositely rotatable turbinedics for dividing the rotary system of the turbine into two separatehigh pressure stages, blades for opposite rotation carried by saiddiscs, a casing in which said shafts are mounted, said casing having aseparate driving fluid inlet for each of said stages, an opening throughsaid other inner disc at the outer end of one high pressure stage andwithin said wall providing a common high pressure exhaust fluid outlet,the rotary system of the turbine further including a single low pressureblading located between discs carrying one of the high pressure stagesand at greater diameter than said high pressure bladings, said lowpressure blading being in communication at its inner end with saidcommon outlet adjacent said opening, said casing having a single outletand said low pressure stage exhausting to said casing outlet.

RAGNAR OLOV JACOB MLLER.

REFERENCES CITED The following references are of record in the le ofthis patent:

FOREIGN PATENTS Number Country Date 377,048 Great Britain July 21, 1932403,335 Great Britain Dec. 21, 1933 537,917 Germany Nov. 19, 1931V86,432 Sweden Apr. 2, 1936

